无线电导航原理和机载设备简介（Principles of radio navigationand airborne equipment）Principles of radio navigation and airborne equipmentEarly aircraft flying in the air relied solely on landmark navigation - the linear landmarks that looked at roads, railways, rivers, etc.; landmarks such as peaks, lighthouses, road interchanges, etc.; landmarks such as lakes and towns. Later, aviation map, compass, slipstick, clock and other tools and their astronomy, geography, mathematics knowledge by aircrew, according to the wind speed and wind direction calculation route angle, combined with landmark fix route deviation, this work is called "air navigation". This method is the "original", but Lin Bo aviation pioneer is to rely on these things when driving a single engine piston aircraft "spirit of Saint Louis" alone from the west coast of the United States set out directly over the Atlantic arrived in Paris, he flew over the vast the Atlantic is through observation of the sea currents, the night sky in the constellation to identify the direction determine the position. Air navigation is a required course for pilots. The key is to modify the influence of wind on flight path by using the principle of vector composition.With the development of radio technology, every kind of electronic equipment provide accurate navigation information for aircraft: for the Omega Navigation System (OMEGA), intercontinental navigation Loran system suitable for a wide sea level (LORAN-A, LORAN-C), for VHF omnidirectional radio short-range navigation standard navigation system (VORTAC),and some for the military development of navigational beacons and radar system. Now, the global positioning system (GPS), which uses geostationary satellites, has begun to be widely used. But VORTAC is still the mainstream of short-range navigation, and most modern military and civilian aircraft, including civil aircraft and small general-purpose aircraft, are equipped with VOR receivers (VOR, very, high, frequency, ommi-directional, range).VORTAC is a general term for VOR/DME and TACAN. VOR/DME is a civilian system, TACAN is developed for shipborne mobile stations, military tactical air navigation system (i.e. the TACAN navigation system). Both work principles and technical specifications are different, but the use of them is exactly the same. In fact, some VOR/DME and TACAN transmitting stations is built together, using the same frequency, the aircrew, just a VOR beacon. VOR beacons are the most important and important radio navigation points in the world. Many of the VOR stations separated by a distance into a network like distribution, when the signal receiver on the aircraft received the VOR beacon, pilots can determine the relative position of the aircraft and the launch station through a special instrument, if the station signal is band ranging (DME, distance measuring equitment), and also know the plane and the station distance, so as to determine the current position of the aircraft, and to know the degree of the flight angle to fly to the destination.Fundamentals of VOR/DME/NDBVOR:very, high, frequency, ommi-directional, range, VHF omnidirectional radio beaconThe operating frequency of the VOR signal transmitter and receiver is between 108.0-117.95 and MHz. The VOR signal transmitted by the transmitter stations have two: one is the phase of the reference signal of the stationary phase; another signal is changing, at the same time as the lighthouse to rotate searchlights every 360 degrees and launch phase signal to launch various angles are different, and their reference signal the phase difference is naturally different. A signal to the 360 degree (pointing to the magnetic north pole) is in phase with the reference signal, while the signal to the 180 degree (pointing to the magnetic pole) is 180 degrees from the reference signal. The VOR receiver on the aircraft can determine the angle at which the aircraft is at the station, based on the phase difference between the two signals received. That is to say, it is possible to determine which radius of the aircraft is at the center of the station transmitter.The signals sent by VOR stations form 360 "radii" that radiate in all directions, each of which is called a "Radial"".If the plane is located in the flat state: VOR station (the station codenamed POU) the South East, toward the station to station, which changed over the course, to the southwest. Navigation terms: aircraft along the POU 135 Radial (R-135), (inbound) to the station, namely the magnetic heading of 315 degrees at POU, along the R-225, fly away from the station (outbound), namely the magnetic heading of 225 degrees. Note: when the plane along a Radial fly away from the station, which is the magnetic heading Radial number; but when the plane flew along a Radial station, the magnetic heading and the Radialnumber 180.Because the radio signal VOR and television broadcast, radio FM radio, is a straight line, the mountain will be obstructions such as, so even if the distance is very near, on the ground are rarely able to receive a VOR signal, usually to fly up to 2000-3000 from the ground feet to receive signals, fly higher, receiving the distance is far away. At 18000 feet (5486 meters), the maximum receiving distance of VOR is about 40 to 130 nautical miles (1 nautical miles =1.852 kilometers), depending on factors such as visual impairment and obstruction. Above 18000ft, the maximum receiving distance is about 130 nautical miles.DME:distance, measuring, equitment, ranging deviceAs mentioned earlier, some VOR stations with DME, DME in UHF band. But the aircrew ignore its frequency, as long as a good tune the frequency of VOR, the signal is received, after a while, the distance calculated numbers will be displayed on the dashboard. Simple working principle is this: Airborne DME transmitting signals to the ground station on the DME, and receives the DME response back ground signal, measuring the transmitted signal and should sign signal time difference, half the time difference, can be calculated distance between aircraft and ground stations. However, it should be noted that the distance shown on the instrument panel is the distance from the slope of the aircraft to the ground station, and the unit is nautical mile. By the Pythagorean theorem, the plane projection and the ground station in the distance should be slightly less than the distance from the edge. Similarly, DMEdisplay on the dashboard of speed is "oblique", said the plane and station "distance shortening rate", is a unit of festival, it is not equal to the speed, is not equal to the speed. According to the DME display range and speed, can roughly estimate the aircraft ground speed and the time required to reach the station.NDB:non-directional beacon, NDB, or "radiophare"NDB is the oldest electronic navigation device still in use today, with inexpensive Chang Jianyou stations near NDB, where there is no instrument landing system, used as navigation and landing guidance. The name "non directional" means that the signals transmitted by each station in the same direction are not the same as each other in VOR. The NDB signal receiver on the aircraft is called ADF (automatic, direction, finder, azimuth indicator). The instrument head of ADF has only one pointer, and when the NDB signal is received, the pointer of ADF points to the direction in which the NDB station is located. If the plane flew straight toward the station, pointer is pointing to the front, when the plane flew over the station and continue to fly forward, the pointer will turn 180 degrees toward the rear.Introduction of airborne electronic navigation equipmentHere is the first clear look at: VOR and NDB are respectively the ground stations, transmitting VOR signal and NDB signal to the plane Nav1, Nav2 and ADF receiver in FS98, Cessna182S or Shift-2 button fly below Mouse click on the dashboard "avionics master switch control panel you can see these receivers (alsosee airborne DME, automatic control panel driving equipment).The three receivers, Nav1, Nav2 and ADF, have a circular instrument head mounted on the right side of the aircraft's main dashboard, in addition to the control panel, indicating specific navigation information.The instrument heads connected to the Nav1 and Nav2 receivers are called OBI, OBI1 and OBI2, respectively. The airborne DME also connects to a rectangular digital header,Install on top of these three round heads.COM1 and Nav1 panelsCOM1: VHF radio station, frequency range 118.0-136.975MHz.Nav1: can receive VOR signal and complete ILS signal, frequency range 108.0-117.95MHz.Nav2 panelNav2 is only used to receive VOR signals. Click the number with Mouse to change the reception frequency.ADF panelReceive NDB signal, frequency range 200-400KHzAirborne DME panelThe number on the left is the calculated distance and speed. The R1/R2 switch on the right is used to toggle the DME calculations that show Nav1 and Nav2.Responder panel (transponder)Receive air traffic control radar signals, and respond to the launch of four bit digital signals to air traffic control radar, allowing air traffic controllers to see the plane's position on the radar, or even height.Autopilot control panel (autopilot)DME headerDisplays distance, speed, and time to the selected VOR station from left to right, with Nav1, Nav2 display switches below.OBI2The Omni-Bearing Indicator, the instrument connected to the Nav2 receiver, displays the VOR information.OBS knobOmni-Bearing Selector, so that the dials rotate to select the line (Radial)CDI pointerCourse, Deviation, Indicator, line deviation indicator,indicating the current position of the aircraft on the selected route (Radial) of the OBS, leaning to the left or leaning to the right.To/From/Off signThe triangle represents the To upward; the triangle down indicates From; the red white bar indicates that Off-- has not received the selected Radial signal of the OBSOBI1Omni-Bearing Indicator, the instrument connected with the Nav1 receiver, besides the function of OBI2, it also shows the horizontal and vertical position information of the approach landing of instrument landing system (ILS).GS signThe To/From/Off flag moves below. The GS flag is added to indicate whether or not the ILS (Glide Slope) signal is received. The red and white bars indicate that the signal cannot be received. At this point, the slide indicator is not activated and does not work.Glide slope pointerIndicates the deviation between the current height of the aircraft and the required height of the ILS slipway.ADFThe Automatic, Direction, Finder, and header connected to the NDB receiver are called "azimuth indicators"".After receiving the signal, the pointer points directly to the location of the station.The knob and dial are purely mechanical auxiliary display devices, independent of pointer pointing and signal reception.The function of the knob and dial is to indicate the degree of difference between the heading to be taken from the station and the current course of the aircraft. The chart shows, stations in the left front of the aircraft, the deviation angle between 20-25 degrees.Sum up:1 and VOR are ground-based transmitting stations, and Nav is an airborne receiver.2, receiver Nav has control panel, press Shift-2 to open is the control panel, in the above can adjust the Nav receiving frequency.3, receiver Nav and instrument head, called OBI, it is installed on the main dashboard of the aircraft to the right, showing specific navigation information.4, the whole OBI (instrument head) consists of four parts: CDI pointer, To/From/Off mark, OBS knob, dial.5, the instrument head OBI1 connected by Nav1 itself can indicate the VOR information (same as OBI2).6, in order to indicate the ILS information of the instrument landing system, OBI1 has more than one GS sign and a glide path pointer over the OBI2. The GS flag indicates whether to receive the signal, the glide slope pointer, and the CDI two pointers, respectively, indicating the horizontal and vertical position information of the ILS.The next article begins with a detailed description of how to navigate and land using VOR/DME, NDB, ILS signals, and airborne electronic devices. But first we must understand the principles mentioned above and memorize the concepts and their abbreviations.Redstar (CFSO002)。